Pore structure and gasification activity of coal and coke studied by small-angle X-ray scattering

Carbonisation is one of the important methods to improve the utilisation of coal. The structural composition of coal plays an important role in coal carbonisation. This work used small-angle X-ray scattering (SAXS) to investigate the pore structure of three kinds of raw coals with different carbon content derived from Xingtai City, Hebei Province, China. The structures of the corresponding cokes obtained through carbonisation at 1200 degrees C were investigated by elemental analysis and SAXS. In addition, the gasification reaction of the three cokes (C1, C2, C3) with CO2 were studied by thermogravimetric analysis. The SAXS results indicate that the surface fractal dimension increases while the pore size decreases, and the pore distribution became wider after carbonisation. In addition, all coals and cokes present a positive deviation from Porod's law, indicating that there is a micro-fluctuation of electron density in the samples. Besides, it exhibites a negative correlation has been found between the degree of deviation from Porod's law and the carbon content. The gasification reactivity of cokes C1 and C3 in CO2 are higher than that of C2, indicating that the pore structures affect the gas reactivity of the three different metamorphic degree cokes in CO2.

Automated summary

This study investigated the pore structure changes of three different carbon content raw coals during coal carbonisation using small-angle X-ray scattering (SAXS), and studied the structure of the corresponding cokes through elemental analysis and SAXS. The results showed that the surface fractal dimension of the cokes increased while the pore size decreased after carbonisation. In addition, all coals and cokes deviated from Porod's law, indicating a micro-fluctuation of electron density in the samples. The gasification reactivity of the cokes in CO2 varied, with C1 and C3 showing higher reactivity than C2, suggesting that pore structures affect the gas reactivity of different metamorphic degree cokes in CO2.